Recovery of the products of destructive hydrogenation



Oct. 31, 1933. M. PIER El AL 1,933,059

RECOVERY OF THE PRODUCTS 0F DESTRUCTIVE HYDROGEN Filed Sept. 9, 1929 is *u 4 x g Pier Earl Wmlier kg-$4 mmvrons. BY Y 5% M ATTORNEYS;

Patented Oct. 31, 1933 RECOVERY OF THE PRODUCTS OF DESTRUCTIVE 'HYDROGENATION Mathias Pier, Heidelberg, and Karl Winkler, Ludwigshafen-on-the-Rhine, Germany, assignors, by mesne assignments, to Standard-I. G. Company, Linden, N. J., a corporation of Delaware Application September 9, 1929, Serial No. 391,508, and in Germany September 22, 1928 4 Claims.

This invention relates to improvements in the recovery of the products of destructive hydrogenation and cracking processes which are hereinafter referred to for the sake of brevity as the 5 conversion of distillable carbonaceous materials by heat treatment.

The gaseous and vaporous products which leave the reaction vesselsduring the destructive hydrogenation of distillable carbonaceous mate rials such as coal, tars, mineral oils, extraction, conversion, distillation products thereof and the like, or during the cracking of mineral oils, tars and the like, and which contain volatile sulphur compounds and difiicultly condensable hydrocarbons in addition to readily condensable hydrocarbons, are as a rule Washed with a washing oil, after the readily condensable products have been removed by cooling, in order to remove as completely as possible the non-condensed hydrogo carbons and the sulphur compounds, which during the condensation are only partly dissolved by the condensate. The pressure is preferably not released from the gases before the said washing process is complete in case pressure be employed. I

We have now found that the washing can be simplified,. and other advantages may be obtained at the same time, by simultaneously carrying out the condensation of the vapors, and

the washing of the gases by means of a washing oil, which is a solvent for sulphur compounds and hydrocarbons. As examples of washing oils may be mentioned for example hydrocarbon oils of high boiling point, such as tar oils, middle oils, mineral oil fractions of high boiling point range, destructive hydrogenation products and the like. The process in accordance with the present invention is preferably carried out by spraying the washing oil into the gases and vapors leaving the reaction chamberbefore they enter the condenser. In this manner an excellent washing out of hydrocarbons and sulphur compounds is effected in the condenser simultaneously with the condensation. of the vapors.

The process thus becomes much simpler in operation, since by working in this manner a special plant for the washing is dispensed with. Moreover the effluent gases and vapors are cooled to a certain extent by the washing oil itself.

By a suitable choice of the quantity and temperature of the washing oil the cooling may even be effected wholly or atleast to the greater part in this manner. It is-also advantageous to work in such a manner that the products leaving the 5 reaction and the washing oil are introduced together into the condenser from below, because in this manner an active and thorough agitation of the gases and vapors with the washing oil is secured. The condensed anddissolved reaction products are collected in a special vessel where 50 they are separted from the uncondensed gases which are free to a great extent, or practically completely from the hydrocarbons and the sulphur compounds. If the washing is carried out under pressure, the gaseous hydrocarbons, sul- 5 phuretted hydrogen and the like may be obtained from the mixture of .washing oil and condensed products byfractionally releasing the pressure. The washingoil may be separated and returned for employment in the process again.

The destructive hydrogenation process referred to above is usually carried out at temperatures of between about 300 and 700 centigrade and preferably at between about 380 and 550 centigrade. Catalysts immune from poisoning by sulphur are preferably employed in the said process, and in particular such comprising a metal in a free or combined state from .the sixth group of the periodic system such as may also be carried out under pressure.

The present invention will be further described with reference to the accompanying drawing which represents in a diagrammatic manner a plant which is particularly suitable for carrying out the process according to this invention. N

Referring to this drawing in detail, hydrogen is introduced at valve 1 and pumped by pump 2 into the pipe 3 at the end of which it is mixed with carbonaceous materials introduced by means of pump 5. The mixture of hydrogen and carbonaceous materials is then passed through the preheating coil 7 and from thence to the preheating device 9, heated by electrical means and in which it is brought to the reaction temperature. The hot materials enter at 10 into the reaction vessel 11 filled with a suitable catalyst. 'In this vessel the, materials undergo destructive? hydrogenation. The converted vapors. leave vessel 11 at 8, pass through pipe 12 and are brought at 15 into direct contact with washing oil supplied by means of pump 19. The mixture of vapors issuing from the destructive hydrogenation and of washing oil is then led' into the condenser 16 in which the vapors of the constituents liquid at ordinary temperature are condensed. The mixture of liquids and uncondensed gases is passed by way of pipe 20 into the vessel 17 from which the liquids may be withdrawn by way of valve 18 while the gases leave vessel 1'7 at 21 and are withcUawn from the plant by way of valve 22 or recycled by way of pipe 23. From the liquids leaving the vessel 17 at 18 the lighter constituents may be separated by distillation. Part of the heavier oils is used again as washing oil.

The following example will further illustrate the nature of this invention, but the invention is not restricted to this example.

Example A middle oil obtained by fractional distillation from a brown coal low temperature distillation tar and containing about 2.0 per cent of sulphur is treated with hydrogen at a temperature of from 450 to 470 centigrade and under a pressure of 200 atmospheres in the presence of a catalyst prepared from molybdic acid and zinc oxide. A washing oil having a boiling point of above about 200 centigrade, for example an oil obtained bythe same process, is sprayed into the gaseous mixture leaving the reaction vessel, which contains practically the whole of the sulphur in the form of hydrogen sulphide. The mixture which has already been cooled to a certain extent by the addition of the washing oil is simultaneously further cooled in a'condenser, and a condensate is obtained'which consists of the washing oil and the readily condensable products, and in which the major part of the hydrogen sulphide as well as the diflicultly condensable hydrocarbons are dissolved. The effluent gases contain less than 0.3 per cent of hydrogen sulphide and only a small quantity of gaseous hydrocarbons. They can be again employed directly for hydrogenation without injury to the tubular conduits by hydrogen sulcontent of the initial material and on the quantity of diificultly condensable hydrocarbons which are produced during the reaction, the enrichment of which in the circulating gases must be avoided.

What we claim is: 1. In the recovery of hydrogen from the hydrogen-containing gases and vapors obtained in the, conversion by heat treatment of distillable carbonaceous materials by washing thesaid gases and vapors with a washing oil which is a solvent for sulphur compounds and hydrocarbons, the step of introducing the washing oil into the mixture of gases and vapors leaving the reaction zone and prior to substantial condensation thereof, and condensing substantially all of normally condensable vapors while said gases and vapors are in contact with the washing oil and while providing for a sufficient indirectheat exchange with a cooling medium.

2. A process for recovering the hydrogen present in the gases and vapors issuing from the destructive hydrogenation of distillable carbonaceous materials in a reaction zone and which contain hydrocarbons and volatile sulphur compounds which comprises washing said gases and vapors directly after leaving the reaction zone with a high boiling hydrocarbon oil and condensing substantially all of the normally condensable vapors while said gases and vapors are in contact with the said hydrocarbon oil and while .providing for a sufficient indirect heat exchange with a cooling medium, thereby separating from the hydrogen the condensable vapors as well as 3. In the recovery of the reaction products from the gases and vapors obtained in the destructive hydrogenation of distillable carbonaceous materials under pressure by washing said gases and vapors with a washing oil, the step of introducing, as a washing oil, a hydrocarbon oil of high boiling point into the mixture of gases and vapors directly after issuing from the reaction zone and without releasing the pressure thereon, and condensing substantially all of the normally condensable vapors while said gases 'and vapors are in contact with said hydrocarbon oil and while providing for a suiiicient indirect heat exchange with a cooling medium.

i. A process for the destructive hydrogenation of carbonaceous materials, which comprises treating a middle oil with hydrogen at a temperature.

of from 450 to 470 centigrade and under a pressure of 200 atmospheres in the presence of a catalyst prepared from a molybdenum compound, spraying a washing oil having a boiling point above about 200 centigrade into the mixture of gases and vapors directly after issuing from the reaction chamber, and condensing substantially.

all of the normally condensable vapors while said gases and vapors are in contact with the said hydrocarbon oil and while providing for a sufficient indirect heat exchange with a cooling medium.

MATHIAS PIER. KARL WINKLER. 

